Systemic Delivery of Tumor-Targeted Bax-Derived Membrane-Active Peptides for the Treatment of Melanoma Tumors in a Humanized SCID Mouse Model

Abstract

Melanoma is a highly metastatic and deadly form of cancer. Invasive melanoma cells overexpress integrin a v b 3 , which is a well-known target for Arg-Gly-Asp-based (RGD) peptides. We developed a sophisticated method to synthetize milligram amounts of a targeted vector that allows the RGD-mediated targeting, internalization, and release of a mitochondria-disruptive peptide derived from the pro-apoptotic Bax protein. We found that 2.5 mM Bax[109-127] was sufficient to destabilize the mitochondria in ten different tumor cell lines, even in the presence of the anti-apoptotic Bcl2 protein, which is often involved in tumor resistance. This pore-forming peptide displayed antitumor activity when it was covalently linked by a disulfide bridge to the tetrameric RAFT-c[RGD] 4 -platform and after intravenous injection in a human melanoma tumor model established in humanized immuno-competent mice. In addition to its direct toxic effect, treatment with this combination induced the release of the immuno-stimulating factor monocyte chimoattractant protein 1 (MCP1) in the blood and a decrease in the level of the pro-angiogenic factor FGF2. Our novel multifunctional, apoptosis-inducing agent could be further customized and assayed for potential use in tumortargeted therapy.

Multifunctional Glycoconjugates for Recruiting Natural Antibodies against Cancer Cells

“…We selected a well‐known cyclopeptide containing the triad sequence Arg‐Gly‐Asp (cRGD), which is one of the most potent ligand for the α v β 3 integrins that are overexpressed in tumor microenvironment . We previously demonstrated that the multivalent presentation of cRGD onto a cyclopeptide scaffold provides an efficient tumor delivery system and imaging agent especially for fluorescence‐guided surgery . Here, we synthesized fluorescent mono‐ and tetravalent RGD‐based conjugates (Scheme ) to evaluate their binding potency.…”

The role of integrins in melanoma: a review

“…Furthermore, Karageorgis et al 64 . described a new and sophisticated method of inducing cellular apoptosis by using integrins.…”

Synthesis and Biological Characterization of Monomeric and Tetrameric RGD‐Cryptophycin Conjugates

“…Previously, RAFT‐ c (RGDfK) 4 was conjugated to a Bax proapoptotic protein derived peptide across a disulfide bridge (RAFT‐c[RGD] 4 ‐S‐S‐depsi‐cgg‐Poro2D). This conjugate displayed a dose‐dependent toxicity against Me275 and Colo829 human melanoma cell lines and induced tumor growth inhibition in Me275 xenografts . However, the RAFT‐poropeptide conjugate showed a biological activity in the micromolar range, and, therefore, high amounts of the compound were necessary for the treatment.…”

“…In agreement with the data presented above,the multimeric conjugate 6 showed approximately three-fold increased activity Finally,c onjugation of the tetravalentR GD-ligand to the antimitotic agent cryptophycin across intracellularly cleavable linker,h as dramatically improved the potencyo ft argeted SMDC based on this ligand, compared to the previously reported RAFT-c[RGD] 4 -S-S-depsi-cgg-Poro2D conjugate. [23] These results underscore the importance of using highly active cytotoxic agentsi nthe context of targeted therapy and show promise for future applicationo ft his payload and its derivatives.…”

“…This conjugate displayed ad ose-dependentt oxicity against Me275a nd Colo829 human melanoma cell lines and inducedt umor growth inhibition in Me275 xenografts. [23] However,t he RAFT-poropeptidec onjugate showed ab iological activity in the micromolar range, and, therefore, higha mounts of the compound were necessary for the treatment. To reduce the dosing and increaset he efficacy, the application of more active agents was envisioned.…”